ENGINEERING SKILL OF SPIDERS. 



221 



that a wire suspension bridge is swung across a valley or stream without 

 engineering skill, as to think such spinningwork structures are wholly 

 without handicraftmanship of some sort. 



The Speckled Tubeweaver (Agalena ncevia), which is probably the 

 most abundant familiar spider of our fauna, affords admirable illustra- 

 tions of this facility. In a stable at Almora, Wallingford, the 

 ^*®^* ^ following form of a sheeted wel) of this species was observed. 

 Tlie upper sash of the stable window had been lowered for pur- 

 poses of ventilation, thus probably rending the original snare. But in one 

 of the upper corners of the window frame and within the space thus left 

 open, Ncevia had renewed her web. (Fig. 208.) The tube was in the cor- 

 ner, and of rather feeble character, but the pouch was doubled up some- 



FiG. 209. .^galena's web with suspension lines and trestles between the bars of a fence. 



thing like a roll, and extended entirely across the window. For about two- 

 thirds of the way it was an ordinary sheeted snare. Then it flared upward 

 and was attached to the upper part of the window frame, and was contin- 

 ued to the opposite side of the window with rather straggling lines. As 

 though to support this structure at either end, a series of strong and very 

 straight taut brace lines was extended downward from either end as shown 

 in the figure. No conclusion is possible except that this was done for the 

 purpose of staying the drooping pouch of the snare, and this, of course, 

 implies intelligent engineering. 



The example cited is only one of many which might be presented 

 from my somewhat extended and varied studies of the Speckled Tube- 



